Hall of Infinite Doors

Squealing in terror, you drop to the now unstable floor, covering your head with your hands and trembling nearly as hard as the ground beneath you. You hear the sounds of splintering stone as the stalactites begin to fall and shatter, but in another moment they are drowned out by the earsplitting CRACK of the rock you're cowering on suddenly splitting in two, one end upheaving and tipping you into the massive, rotating maw of an ancient Stonewyrm, perhaps the very one that chewed out these tunnels in ages past. You wonder what disturbed it from its slumber, but it's not something you have much time left to consider.